I like that one!
Kangaroos: a troop or mob
Tigers: an ambush or streak
Two I recently found: a clutter of cats and a cowardice of dogs😄
What would be really weird is to find out about a mass of flying insects being called something other than a swarm
I knew about a clowder of cats. But I could see clutter being the original (it is a word with an existing meaning), and being altered to clowder. Of course, clutter of cats could relate to litter of kittens 
Yeah, I think there are just multiple names for it… which is confusing!
multiple names for group of cats (from wikipedia):
clowder
cluster
clutter
glaring
pounce
kindle (kittens)
litter (kittens)
pillow (kittens)
The collective name for the venery of cats (proposed) :
A profusion of veneries
or should it be a confusion of veneries? :)
And groups of foxes go by four names …
a skulk, a leash, a troop, or an earth.
Cute Photo
We might well ask: in a school of fish, which one is the teacher?
The biggest one probably- the whale shark?